Adaptive flash with pulse width modulation

An imaging system, comprising:

• a light-emitting diode (LED) array, each LED of the LED array being configured to illuminate a respective region of a scene;
• an ambient light sensor configured to sense time-varying ambient light that is present in the scene and, in response to the sensed time-varying ambient light, produce a time-varying ambient light signal;
• a controller configured to:
• determine an ambient light frequency and an ambient light phase of the time-varying ambient light signal;
• and
• electrically power the LEDs of the LED array with respective pulse-width modulation (PWM) electrical signals to produce illumination, the PWM electrical signals having a same amplitude, each PWM electrical signal having a respective duty cycle that corresponds to a specified illumination intensity in a respective region of the scene, each PWM electrical signal having a respective PWM phase that is synchronized to the ambient light phase;
• and
• a lens configured to direct the illumination toward the scene to illuminate the scene.

A method for illuminating a scene, the method comprising:

• sensing time-varying ambient light that is present in a scene to produce a time-varying ambient light signal;
• determining an ambient light frequency and an ambient light phase of the time-varying ambient light signal;
• electrically powering light-emitting diodes (LED) of an LED array with pulse-width modulation (PWM) electrical signals to produce illumination, each LED of the LED array being configured to illuminate a respective region of the scene, the PWM electrical signals having a same amplitude, each PWM electrical signal having a respective duty cycle that corresponds to a specified illumination intensity in a respective region of the scene,
• at least one of:
• the PWM electrical signals having a same PWM frequency that is an integral multiple of the ambient light frequency, or
• each PWM electrical signal having a respective PWM phase that is synchronized to the ambient light phase;
• and
• directing the illumination toward the scene to illuminate the scene.